The Community Multiscale Air Quality (CMAQ) modeling system extended for hemispheric-scale applications (H-CMAQ) incorporated the satellite-constrained degassing SO₂ emissions from 50 volcanos across the Northern Hemisphere. The impact on tropospheric sulfate aerosol (SO₄²⁻) is assessed for 2010. Although the considered volcanic emissions occurred at or below the middle of free troposphere (500 hPa), SO₄²⁻ enhancements of more than 10 % were detected up to the top of free troposphere (250 hPa).